Automatic telephone system.



' B. [LVI/nus.; AUTOMATIC TELEPHONE SYSTIENI.A

APPLICATION FILED N0V58 ISIS.

tentedl'Nov. 6, 191?? -v 2 sHEUssHEET 1.

BEST AVAILABLE GIGI?y B. D. WILLIS. AUTOMATIC TELEPHONE sYsIEI/I.

` APPLICATION FILED IIov.8. I 9I5. 1,245,650;

vPatente Nov. ,6, 1912.

2 SHEETS-SHEET 2,

BEST AVAlLABLE COF`v BERNARD D. WILLIS, F CHICAGO, ILLINOIS, ASSIGNOR TOI AUTOMATICK'ELEGTRIG COMPANY, 0F CHICAGO, ILLINOIS, A GGRPORATIDN 0F ILLINOIS.

AUTOMATIC. TELEPHONE SYSTEM Speccsiton of Letters Patent.

Patented N pv. 6, 1917.

Application le'd November 8, 1915. Serial No. 60,265. i

1/ '0 all whom t 'mag/.concern Be it known that I,v BERNARD I).

l e citizen of the United States of America,

and a resident of Chicago,county of Coeli, and State of Illinois, have invented certain new andy useful Improvements in'Automatic Telephone l Systems, lof which tliel following is a specification. l.. A

My invention relates to automatictelephone systems and more particularly to those systems inrwhich fthe central oice apparatus is controlled by impulses -delivered'over the two sidesof 'thelinefinV series.

.In systems'of the .above general character it has been thecom'mon `practice to control the selectorlnd connector switches through Y themedmm of so called fast and slow relays,

tlieserelays being responsive, respectively,

'Y to interruptions of the linecircuit andy to a Series of such interru itions.

A wellknown'type oi: selectorsvvitch, for example, has 'a controlling. relay v.which sends an impulsev to a vertical operating magnet at each interruption of the line circuiti At thev same timey .impulses .aresent itc a slow relay ywhich energizes at .the first impulse A .and retains its armature in an operated position `during a series of impulses.. vAt the end or `the series of impulses the yslow-relay retract-S its armature thereby closing 'e circuit whereby thewipers are started rotat- WrLLis,

is responsive to the-prolonged Iinul impulse.

In the operation of the system, the last impulse of'every series eii'ectivel energizes the special relay above mentione which reley controls certain circuits whereby, 1n the case ofia selector switch, the rotary movementto.-

select an idle trunkrisinitieted,u sind, in the case of a connector. Switch, the controlof the side switch is effected.

A further object of my invention is thel provision of a new and improved method of controlling the disconnection. of the switches in a system of the yabove character'. It has formerly been lthe practice to use for this purpose a slow actingrelease relay.. which denergizes only when the line circuit is permanently opened, as by hanging up the receiver. I prefer to use a. pair of locking relays which, in addition to other functions, lserve to control the reiease of el selector and to provide a holding circuit or preceding switches during the time a selector switch p ing to automatically select an idle trunk l iine. In the common type of connector,

switch' a slow relay similar' to the one men toned above is used to control a` so-called side switch through 'the medium of a1 private magnet, the side switch being advanced after each series of impulses to change local circuits in preparation ,for the next series ot' impulses. Y

n Theobject of my, in`vention is to provide a new. and moreeflicient methodoi shifting use `of a relay responsive to the time intervul between two series of'iinpulses.

ling relay, gire provided with a relay which,

' is slow to energize and is, tlierei'ore,.irre

sponsivc to impulses of lordinary length, but

the .local circuits of selectoren'dconnector switches, whereby I um ebleto` avoid the is receivingv impulses, after which the control i's shifted in part to a slow acting relay whilevthe selector is rotating, and finally, at the cessation of the rotation, thecontroiis shifted to relays in the succeeding selector or, connector, iis the case may' be. f'

.In the oppiication of the principles of my invention to selector'l and 'connector switches of standard type a variety of modi` cations and-circuit changes rare'recpiired, all of which haveibeen provided v1 and .will be hereinafter fully explained, reference being had tothe accompanying drawings.

I have shown iii-Figs. l end 2, takenin orderwitlifthe lines et the ends thereof iny alinement, :incomplete circuitconnectionbetween o calling,F substation A and e called substation A in av system embodyinghe .principles oi'my invention. The seid corif nection .has been established through the medium ofthe individual' l-ineswitch C, the selector switch E, andthe connector switch'F. u

191.0. As herein represented it consists of' the receiver '2, transmitter 3, receiver hook .4, ringer 5 and condenser 6. Being an autonm'tic substation it is also provided with a pui-r ot' impuise springs 8 and 9 controlled lby the impulse wheel 7 through the medium ci' a finger hole dial (not shown). .In ac- .1. 19.0y The substation A (Fig. l) miiy be of the",v

cordance with my invention the last impulse tooth carried by the impulse wheel 7, indicated by reference character 10, is made somewhat longer than the rest of the impulse teeth for a purpose which will be explained hereafter.

The line conductors 12 and 13 of the substation A are connected at the exchange to arm 19. The plunger arm 19 and the cut olf armature 20 are controlled by the magnet 16 which has two windings; one of which, the pull in winding 18, operates both the plunger arm and the cut off armature, While the other, the holding winding 17, is only strong enough to operate the cut off armature and to hold the plunger arm in an operated position after it has been op; erated by the pull-in winding. When the 4plunger arm is operated, the"plunger is forced into a bank of contact springs, forcing the springs 26, 27, 28 and 29 into engagement with contacts 30, 31, 32 and33, respectively. Although only one set of springs and contacts (26 to 33, inclusive) is shown, it is lunderstood that each line switch is provided with a plurality of suchsets, each set forming the terminals `of a trunk line leading to a first selector switch. Each trunk line is connected in multiple with the` corresponding springs of all the line switches of the group which is controlled by the master switch D. The line switch C is -controlled by the 'subscriber through the medium of the line relay 14.

The master switch' D is of the general type disclosedin British patent to R. W. James, No. 26301 of 1906, being, however, more nearly of the particular type disclosed in British patent toT. G. Martin, No. 1419 of 1910 'above referred to. The function of the master switch, as is well known, is to mtfntain the plungers of all the idle line switches in position before=the terminals of an idle trunk line.

Accessible to the line switch C is shown a selector switch E; which is of the general type of selector switch disclosed in United States Letters Patent No. 815,321, granted' March 13, 1906, to'Keith, Erickson, and Erickson, except that the so called side switch is omitted and thc circuits are modified to enable the switch to operate' 1n a system in which the central oliice apparatus is controlled by impulses delivered over the two sides of the line in series. There' are, furthermore, a number of other modifica- Among other details the selector E comprises a bank of contacts arranged in horizontal rows or levels, which contacts are, adapted to be engaged by a set of wi ers 100, 101, and 102 carried upon a shaft not shown) which has a vertical movement controlled by thc vertical magnet 53, and a rotary movement controlled by the'rotary magnet 54. The operation of the variou.c partsof the switch are controlled through the' medium of the double wound line relay 50. Means-'for permittingy the switch to be restored to normal position are provided in the release magnet 57, which, upon energizing, withdraws the retaining pawls from the shaft. The contacts 88 and 97, are closed only when the shaft has been raised one ormore steps from its lowest position. The relay 59 iswconstructed in a manner such that it is especially adapted to carry out-the objects of my invention The said relay is wound to a very high resistance and it is provided with a heavy slug of copper -on the end of the core whichis next to the y ner in which this is brought about will be more fully explained in connection with the detailed description of the operation of the system as hereinafter disclosed.

The selector switch E has access to a number of connector switches, one of which is shown at F. This connector switch may be of the general type ,of connector switch' disclosed in United States Letters Patent No. 815,176, granted March 13, 1906, to Keith,

Erickson, and Erickson, t'oe'circuitslbeing modified, however, to adapt the switchl to the hereinbefore mentioned two wire si'ies method of control, and also to accomplish the several objects of my invention. Among other details the connector F comprises a bank of contacts arranged in horizontal rows or levels, which contacts arc adapted to bc engaged by a Set of wipers 180, 181, and 182 carried upon a shaft (not shown) which has a vertical movement controlled by the vertical magnet 117, and a rotary movement Controlled bythe rotary magnet 118. The usual side switch comprising llw. wipers 131 and 132 is controlled by the private magnet 116 in tho well' known manner, except that the private magnet is itself controlled in a man- 60 ,l wind i ng 18.

BEST AVAlLABLE COF" ner peculiar to my invention.y The opera'- tions of the various parts of thesWitch are controlled through the medium ofthe double rent by means of the double Wound answeri'fjmg bridge relay 113. The ringing relay 128 affords. means for projecting ringing ,o current over the called line to Signal the called subscriber. Means for permitting the switch to be restored to normal position are provided in the release magnet 129, which,

upon energizing, withdraws. the retaining l5 Vpawls :from 'the shaft. The contact 130` closes only whenthe shaft has been raised one er more steps from its lowest position. The relays 122 and 127 are similar to relay 59 of the first selector, that is,y they will '20 not attract their armatures when receiving the ordinary operating impulses. Relays 126 and 123 will be referredto hereafter as Wiper eut o iid and busy test relays, respectively, and their functions will. be explained more fully at the proper time.

The individual. line switch C is similar to the line switch lC and is controlled along f with a number of other line switches by a master switch which may be the master switeh'l) or a similar one; The substation shown at A is in all respects similarto the substation A. For supplying operating and talkingcurrent I have shown at B a battery having its positive terminal grounded. I have also shown a generator Gren. for supplying ringingcurrent and an interrupter I for intermittently operating the ringingrelay.V yAt T I have shown a busy signaling machine wipi'iaratus i will novvproceed to a ldetailed explanation of the operation of the Same. The various operations taking part in the \estal lishing of the connection4 shown in the .liawings, .will be fully covered, particular attention being paid to the features of my invention.

Referring now to Fig. 1, the subscriber at sulfistation A, upon removing` his receiver' 5o to initiatea call, completes an energizing circuit tfoi' the line relay 14. of the line switch (l over the following path ground at (i2,

contact springs 25 and 24, line conductor 12., to and through substation A, line conductor 13, contact springs 22 and 23-Windingv ot line relay 14 to battery iB. .lheline relay is energized over the above circuit and upon attracting its armature, completes a' circuit from ground at G tothe pull in The pull in Winding, upon energizing, attractstlie plunger arm 1S) and the cut oit'. armature 20; the former, by means of its plunger', forcing; the springs 2li-29 inclusive into engagement, respec- 55 tively, with contacts 30-33 inclusive, and

' 12 and 13 from groun and battery, r tively, by separating contact springs 24l wound line relay 110 which also serves to i 5 supply talking battery to the calling line. l

rlhe called line is providedwith talking cur' Having given a' general description otV the f curred in response to theremoval of the'i'cthe latter-disconnectin the A,line conductors.

y. relay 50 to batteryB.l Upon energizii'i'gy the" linerelay completes/a circuit'foijfrelay 55 as follows: 'ground atti?, eontactsprings ,642 and 65, contact -springsl7 1` and 72, andwind- 4 ing of 'relay-55' vto i batteryk BJ y'Relay v55,` 85 upon energizing, completes a holding cir'- i cuit which extends back to thelinefswiteh C over the'following path :.'g'r'ouncil'r4 at, G8, contact springs and 79, Contact springs 67 and 66, contact 31, spring -27 and holdingwind- .9f0

ing 17 of'linesivitch'G 'to battery B Al-i `l though the circuit .through the line relay 14j has already' been broken, it retains its armature long eno-ugh forthe above'described' holding circuit-Lo be established andto't'ake eii'ect. A branch ofthe holding circuit eXj tends from spring 27 over Wire 21 to=mul tiple .test contacts in the banks ofieonnectors having accesslto the line'of substation A, where. by 'a ground potential on these'test contacts, the sai'ddine is' 'made busy.

Returning now to relay 55, of selector E, j upon the energization ofthis relay, ground at G is extended byway of contact springs- 8() and 81 to Contact spring 65 whereby relay, 55 is provided with an energizing ciri cuit independent of the contact Lsprings 64 and/(S5.` Also a circuit is completed `for the? A relay 58 as follows: ground at G8, contact J springs 82 and 83, and winding voli-relay 58 115 magnet 53. 'Ihe closure4 of contact springs pare circuitswliich willjbe-explained laterw The foregoing operations have r.alllocceivdi from the hoQl. The. subscriber at"- substation `A may''noivpperateA hisfdial in accordant-,e with tbetiifstfdigitot the/desired number, thereby"breaking 'the contiiiuity' .olE his loop :r number ot' times anilfresulting" 125 in a correspondingnumber of `i`le`-iiergizations of the line relay 50. '.Ateach deinerv Y f f' ni-ization the line relay'sendsaniuipulsetor the vertical magnet `53-over, tlie.-folla' 'ti to battery B. .'lelay '58, upon energizing, j

tact 87, off normal o contact 88, contactsprings 77 and 76, and winding of relay 58 to battery. A branch of the above circuit extendsto the test wiper 101-from the lower off normal contact spring. Each time the line relay sends an impulse to the vvertical magnet it also sends an impulse to the re- ,lay 59 over the following path: ground at G, contact springs 80 and 8.1, contact springs 62 and 61, contact springsl70 and 69,

and winding of relay 59 to battery B. As previously explained however, relay `59 is not effectively energized by any of these impulses except the last one which is of longer duration than the rest. When thel final impulse comes in, therefore, relay 59 attracts its armature. with the following re 'sultsz by closing contact springs 66 and 68 and separating' contact springs 66 and 67 the holding circuit is shifted from ground at G to ground at G. By separating contact springs 7l and'72 the circuit of relay 55 is broken and an instant later by closing contact springs' 69 and 71 a new energizing circuit for relay 59 is .completed from ground at G8. This latter circuit is immediately broken again by the deinergization of relay 55 but existslong enough to fully lattract the armature of relay 59 which is retained in operated position by the well .known sluggish action until the relay 5() pulls up again after the Afinal impulse and completes the following circuit: ground at (if, contact springs 64. and 65, contact springs 71 and 69, and winding of relay 59 to'battery B. lt will be remembered that a branch of the holding circuit has been traced to contact spring 76 of relay 58. U pon'th'e denergization of relay 55, current flows over this branch circuit from groundat (i0 to contact spring 76 where it divides, one branch extending through winding of relay 58 to batteryB, andthe other branch f extending by way of contact springs 83,;and

84, contact 86, and the Winding of rotary magnet 54 to battery B. As a resultrelay 58 remains energized, although its previous energizing circuit from ground at G has been broken, and the rotary magnet 54 attracts its armature 85, thereby rotating the wipers 106, 101, and 102 u'ntil they stand on contacts which are terminals of the first trunk line of the desired group. .lust before armature 85 reaches its extreme forward position it opens contacts 86 and 87, thereby breaking the rotary magnet circuit and the locking .circuit of relay 58. 'l`he rotary magnet thereupon denergizes but tlierelay V58 may denergize oiwmay not, depending suming, then, that the first trunk line is busy, the relay eremains energized, and, as the rotary magnet retracts its armature, the contacts 86 and 87 will again close and complete the former energizing circuit of relay 58 and the rotary magnet. In this way the wipers are advance( step by step until they reach the terminals of an idle trunk line, when, the test wiper no longer finding ground on the test. contact, the relay 58 denergizes as contact 87 opens. Upon retracting its armature, relay 58 breaks the rotary magnet circuit and its own former locking circuit by separating contact springs 76 and 77, whereupon the wipers 100, 101` and 102 will be brought to rest upon contacts 103, 104, and 105, respectively, these contacts being the terminals of the first idle trunk line. Also, by separating contact springs 73 and 71 the vertical magnet circuit is broken, and by closing contact springs 74 and 75 a circuit is prepared for thel release 'magnet Finally, by closin'g` contact springs 77 and 78, an energizin-g circuit is established for the line Switchs' 105 ing relay 56 as follows: ground at fi", ifi tact springs 68 and 66, Contact 87, oli' normai contact 88, co11tact,sprii1gs 77 and T8, and winding of relay 56 to battery B. Upon. .ein ergizing` the. line switching relay 56, 'sepa 110 rates a pair of contact springs, and 96 in the circuit of the release magnet, and also shifts the two line conductors from line relay 50 to line relay 110 of connector l?. Line relay thereupon energizes over the fol- 115 lowing circuit: ground at G2, winding' 111 4of line relay 110contact springs 13T and 136. bank contact 105. wiper 102, contact springs 92 and 93, previously traced circuit through subscribes loop, contact springs 126 90 and 89, wiper 100,' bank contact 10i-l, contact springs 133 and 134, and winding 112 of -relay 110 to battery B. Upon attracting its armature line relay 110 completes a circuit for relay 119 as follows: ground at (i12, 125 contact springs 141 andA 142, and winding of relay 119 to .battery ll. ltelay H9, upon energizing, prepares a circuit for tin vertical magnet by closing contact springs l-'l6.and 147, and, by closing contact springs 139 v.springs 155 and 15'6, contact springs 144 and 143, and winding 121 ofA relay 119 to battery. A branch of the above circuit provides a holding ground for the selector E and line switch C and may be traced'as follows: contact springs 145, bank contact 104, wiper 101, where it divides, one branch eX- tending by way of contact springs 77 and 78 and winding of relay -56 to battery B, and the` other branch extending byv way of off normal contact 88 and contact 87 Ato where it joins the previously described holding circuit extending to line switch (l. Although the circuits of relays 50 and 59 have already Y been broken, relay 59 retains its armature for an instant in order vto allow suhclent.

time for establishing the above holding'circuit. f

Returning now to the connector lil', we may trace a circuit for the private magnet 116 which extendsv from the junction of con.

tact spring 148 and winding 121, by way of contact springs 168 and 167 and winding of private magnet 116v to battery B. NVe now ave relays 110 and 119 of connector F energized, and current flowing fromground at G13 through private magnet 116, winding 121 of relay 119, and over the holding cir-,

cuit all in parallel.

The subscriber at substation A may now operate hisv dial in accordance with the sec ond digit of the desired number resulting, in this case, in a corresponding number of denergizations of the line relay 110. At each retraction of its'armature the line relay sends an impulse tothe verticalv magnet 117 over the following path: ground at G12, contact springs .141 and 140,'contact springs 147a of vertical magnet 117, and side switch wiper 132 in its first position tobattery B. The vertical magnet, in re-` sponse to these impulses, raises the shaft step by step until the wipers standlopposite the horizontal row of contacts in which are located the terminalsofothe desired line. At the first vertical,- step oli" normal'cont-act 130 is closed and thereafter the relay 127 receives impulses in parallel Withthe vertical magnet over the following path: ground at G12,

contact springs 141 and140, ofiZ normal contact1180, and winding'of relay127 to battery B. vAs has beenp'explained,however, relay 127 is slow to energize and does not nespond to any et these impulses except the last'one,

which is longer than the others. fUpon receiving the final impulse, therefore, relay 127 venergizes for an instant ,and `'breaksthe circuit of the privatev magnet l'11,6 momentarily, thereby allowing the, side `switch lel v4vers v191 ands132 to yadvance to thei'rfsecond ,Y I,positions in the well known manner. Upon ,i energizing, relay* 127 also sends an" impulse torelay 122 by way of Contact springs 169l and 170, but relay 122 is slow vto eiiergize` and does not respond thereto. 4 l t i The subscriber at substation A may now operate Vhis dial in accordance with the third and final digit of the` desired number, resulting as before ina corresponding number o1 denergizations of the line relay 110 which now, side's'witch: wiper 132` beingv in f its second position, sends impulses -to the rotary magnet 118 and also ito the relay :127. Responding to these Aimpulses the. rotary magnet rotates.,the"wipers.180,181 and 1 82 until they restl uponcontacts which are ter-` minals of the desired. line and whichare indicated by reference characters 183, 184 and 185. At the nal impulse relay 127energizes momentarily asbefore whereupon the' private magnet denergizes for an instant and allows the side switch wipers V131 and 132 'l to advance to their third position. Assuming now that the called line was idle, a circuit is completed for the energization of `relay 126 which may be tracedas follows:

ground at G13, contact springs 155 and.156,

contact 'springs 144 and 145, side switchy wiper 131 in its third position,windingof relay 126, winding 125 of relay123, and sideA switch wiper 132 to 'battery 'B. .v Relay 126 is energized over' the above circuit but wind- 'ing 125 is sov designed as toibe'inoperativewhen in series with relay 126'. Upon attracting its armature, relayg126 connects the two line conductors ythrough to the Iwipers- 180 and.A 182, "therebyH completing the connection :betweenithe'calling and the called,

subscribers lines. f .At the same time circuits are established for the test wiper' 181 andv the ringing relay 128. The `former othese circuits extends from ground atl G, by way of Contact springs 158, 1.59 and 160, test wiper 181, and bank contact 184tol the hold-k rot ing winding 201 of the individual line switch C- where., by attractingkcutoi armature 202, the called line i `disconnected from ground. and battery.' 'Gr und fromfthe test wiper `181 'also serves to make the called lineV busy toother connector switches through .the multiple connection of test contact 1,84 with the test contacts of Aother connectors. The

Vcircuit for the ringingA relay'ig6128 is as'ollows: ground at G, contact springs 158 andy 159, contact springs: and 151, windn of tently to project'v ringing current'ffrom the ringing relay 128, ,and interrupterfl 4to. attory B. Upon the completion-'Of the aboye L- Acircuit the ringing inlay. operatesv intel-init# generator; Geni-@lout over the :line fot the,

called. subscriber tothe substation ',YVhen the subscriber at s substation A lremoves' his receiver in responsefto-1the' ringing iioffl'liis' bell he completes, at thejrst denergizationK'v springs 176 and 17 5, wiper 182, bank contact 185, luie conductor 13', to and through substation A, line conductor' 12', bank contact 183, wiper 180, contact springs 172 and 173,

contact springs 162 and .63, and winding 115 oi' rela 113 to battery B. Talking current for the called substation is supCplied over the above circuit through the Win ings of relay 113 which, upon energizing, reverses the ybattery connections to the calling line and also completes a circuit for `relay 123 as follows: ground at G21, contact springs 132 and 131, winding 124 of relay 123,A and Side switch wiper 132'to battery B. Upon energizing, relay 123 breaks the circuit of the ringing relay 128 andalso completes for its winding 124 a circuit which is independent of the relay 113. This circuit may e traced either from ground at G1s or G1".

Beginning at G1, the circuit extends by way of contact springs 155 and 156, contact springs 144 and 145, contact springs 148 and 149, and winding 124 of relay 123 to ybattery B. From G the circuit extends via contact springs 158 and 159, contact springs 150 and 149, and winding 124 of relay 123 to battery B. Briefly stated, the effect of the above circuit arrangement is to connect ground GM to the holding circuit in parallel with ground G13. and to connect the said holding circuit to winding 124 ofrelay 123. The two subscribers may now carry on a conversationwithout further effort on the part of either of them. Should the called subscriber hang up his receiver the relay 113 denergizes and separates the springs 131 and 132, without affecting relay 123, however, for this relay remains energized over an independent circuit. Should the calling 40 subscriber hang up, the line relay 110 deenergizes and ground from -G12 is extended to relay 127 over a path previously traced. Relay 127, upon energizing, extends the same ground to relay 122 which relay, upon at` tracting 1ts armature, disconnects ground Gi3 from the holding circuit and connects it to the release magnet 129. Upon energizing, the release magnet operates to restore the shaft and the side 4switch wipers to their 5 0 normal position. As the side switch wiper 131 leaves its third position the circuit of relay 126 is broken and relay 126 thereupon denergizes, removing ground G1* from the holding4 circuit. As a result the holding winding 17 of line switch C and the line switching relay 56 of selector E denergize, the. former allowing the lunger to be withdrawirffrom th"bank o contacts, and the latter closing a circuit for the release mag- 620 net 57 which, upon energizing, restoresv the i shaft and side switch wipers to their normal position.

I will now describe briefly 'the case where the `called line is busy. It has been men- 65 tioned before that the test contact of 'a busy 'tion ation that I have provided third position to battery B. It will-be seen from the above that a direct ground via the test wiper is connected to the junctionof winding 125 and relay 126 thereby short circuiting relay 126 and causing sufiicient current to flow in winding 125 to energize re- 86 lay 123.l Upon energizing, relay 123 closes a previously described circuit for its locking winding 124-and in addition'connects a lead ktrom the busy signaling machine T ,to one side of the calling line for the purpose of indicating` to the calling subscriber' that the desired line is busy. The circuit may beitraced as follows: Battery B, secondary of busy machine transformer, con-v tact springs 152 and 153, 166 and 165, and over the lower heavy talkin conductor to and through substawhence g it returns over the upper heavy talking conductor and reaches battery B. again via contact springs 133 and 95 134 and winding 112 of relay 110. Upon rcceiving the signal the calling subscriber replaces his receiver whereupon the apparatus is restored -to norma-l substantially as has been described.

It will be seen from the foregoing explana new and effi--A cientv method of switching local selector and connector circuits, after a series of .impulses without' depending time interval between impulses of a series and between two series' of impulses. In additionV I have provided an improved method of controlling the release magnets of selector and connector switches and have also revised the circuits `and vgeneral arrangement in order to enable the parts provided by my invention to coperate with well known elements to form a complete and eflicient mechanism.

WhileI have described one embodiment of my invention I do not wish to be held strictly tothe exact form disclosed herein, for modifications willno doubt suggest themselves to persons skilled in the art. I desire, therefore, to include andhave protected by Letters Patent all forms and modifications of my invention which may come within the scope of the appended claims. i Y

What I claim as my invention is:

1. In a telephone system, an automatic switch having a plurality of operating magnets, a controlling` relayior one of said magnetsresponsive to all" the impulses of a 130 contact springs 90 l in any way upon the 105 series', an auxiliary controlling relay for sponsive to `all the impulsesof a. series, an-

` a locking by said-third relay to said first vrelay matic switch accessible to Aa plurality of operatin another of lsaid magnets `responsive only to the iinal impulse, a third relay coperatin with said second relay to Acontrol said last magnet, and circuit connections wheren anddenergizedresponsiveto said second relay, 2.-ln a telephone system,

a line, an autotrolling relay fora one o saidiiiagnets reauXiliary controlling relayqfor-another of said magnets responsive Vonly to the .final impulse, said impulses 'being over the twosides of saidline in -series and circuit for said second relay under control of said first relay, whereby the said second rel-'ay maybe maintained energized durinlg the operationof said last magnet. 3'. i n

another of said magnets4 said magnets'responsive to a a 'telephone system, an automatic trunk selecting switch having a plurality oat selective movements, actuating magnets .for

'said switch, a controlling relay for one or said magnets responsive to all theimpulses of a series for selecting. a group oi trunks, a second relay forffinitially controlling .another oi 'said' actuating magnets to select an idle trunk in said group, lay irresponsive toall impulses of a series 'exceptthe -last one'aiid a locking circuit Afor said second relay under control or said first relay, whereby said second relay is maintained energized' during the selection of an idle trunk. f f

4. In a telephone a line, an autosystem,

matic switch vaccessible to saidl line, and.

means for controlling said switch by impulses delivered over the two-sides of said line in series, `said means comprising a relay responsive to 'all `the impulses of a series, 1 only to the iinal avsecond relay responsive impulsev of the series, an a third relay con-` trolled jointly by said and second re- `actuating magnets for said switch, aicontrolling `relay1for one of' ll the impulses gota series for selecting a group -ot trunks, a

-secbndrelay of ""said f actuating ,magnets trunkiiilsaid group,

for initially controlling another to select anv idle said second relay irre- `cept the last one,

is energized responsive said line having transmitted ries, means 'said second reswitch having primary and sponsive to all impulses of -said series ex said switchto normal position, vsaid'means l-.controlledjointly by said controlling relays.

7 In a telephone system, a s uhscribers station, an impulse sending vdevice at said and means for restoring station, means included in said device for prolonging ,the final impulse of a series, a line for said station, an automatic switch accessible to said line' and having a plurality of `selecting movements, actuating magnets for saidsvvitch, acontrolling relayfor one of said magnets respons ve to all the impulses of a series for selecting a group of trunks, a

second relay responsive to thefinal impulse of' said series for initially controlling another of said actuating magnets 'to select an idle trunk in said group,fand means for re-A storing said switch to normal position, said means controlled relays.

8 In' a telephone system, `an automatic switch having primary and secondary operating magnets, a lcontrolling relay r'or said primary magnetresponsive tov 'all the iinjointly by said controlling sponsiveonly 'to the iinal impulses ot` a sefor 'closing the circuit of the secondary magnet at one point cessation of the primary movement of said switch, a. locking relay initially energized .prior 'to the by said iirst relay for holding saidcircnit i o eli-at another point and means responsive to the energization oiy said second relay for opening the locking circuit of said third ref lay, whereby the circuit of said [secondary magnet may be closed. 4

9. ln a telephonesystem, an eautomatic switch having directive primary movemen to select a group of trunks and, automatic secondary movement to select an idle trunk line in the selected group, a `trunk release conductor extending'to said switch, a relay v'for' grounding said conductor during the said primary movement, a secondrelay for grounding said conductor during the secondary movement, means 'for initially energizing said relays, and locking circuits for said re lays, respectively, ergized during the said primary ary movements.

.10. In a telephone system, an automatic secondary oper-L atingmagnets and a release magnet, a relay ordirectively controlling said operating magnets, a second relay under control of said and secondirst relay for controlling tliechange over from one operating magnet to the other, and a third relay under control of said second 'relay for controlling ,said release mag- In a teleplione system, an automatic switch having primary and secondary operating magnets and arelease magnet, ai relay for directively .controlling lsaid operating ior maintaining them enpulses of a series, a second control relay re' magnets, a second relay under control of said first relay for controlling the change over from one operating magnet to the other, and a third relay under the joint control of said first and second relays and operative to close an energizing circuit for said release magnet.

12. In a telephone system, a line terminating in an automatic switch having primary and secondary operating magnets and a release magnet, three relays for controlling, respectively, the actuation of said operating magnets, the change over, from one operating magnet to the other", andthe said release magnet, said relays being responsive,-

respectively, to short, long, and prolonged interruptions of the line circuit, und means for producing suitable interruptions in the said relays. 13. In a telephone system, a subscribers line, an automatic switch having primary and secondary operating movement and r'eleasing means, means for extending said line to said switch, three relays lin said switch for controlling, respectively, the operating movement'of said switch, the fchange over from one operating movement to the other, and the said releasing means, said relays being responsive, respectively, to short, long, and prolonged interruptions in the extended line circuit, and means at the. substation on saidline for producing suitable interruptions to operate said relays, whereby connection to another line may be established and disconnection effected.

Signed by meat Chicago, Cook county, I1linois,; this third day of November, 1915.

BERNARD D. WILLIS. Witnesses: s

Cms. M. CANDY, Louis M. LANDA. 

